Electric propulsion systems for motor vehicles have been proposed to completely eliminate emissions; however, as is well known, present technology requires bulky batteries which have to be recharged for long periods of time. The capacity of such batteries provide only limited range for the motor vehicle. One solution to this problem is shown in my U.S. Pat. No. 3,791,752 issued Feb. 12, 1974, where the on-board electrical power pack is required until electrical power can be derived from an electrified highway system. Unfortunately, the capital investment required for such systems is not available at this time and an alternative solution to the long battery charge problem is shown subsequently herein as a preferred embodiment of the present invention.
Automobile manufacturers have been devoting enough efforts through R and D funding to satisfy E.P.A. requirements by utilizing electronic controls to control emissions from I.C. engines over their entire operating range, viz., during acceleration, etc., and over a great range of power demands and wide range of speeds. However valiant such efforts are considered from an environmental standpoint, such efforts to clean up emissions over the entire operating range have been only moderately successful, at best.
The first effort utilizing electronic modulation (and 13th patent found in the U.S. Patent and Trademark Office, Class 123, Subclass 57, containing over 300 issued patents) to control EGR flow and control emissions is shown in my U.S. Pat. No. 3,788,284 issued Jan. 29, 1974.
Hybridization has been recognized where the I.C. (internal combustion) engine is operated at maximum efficiency and lowest possible emissions in a series or parallel configuration with the electric propulsion system as seen in U.S. Pat. No. 4,021,677 issued Mar. 3, 1975. In such a hybrid system, the I.C. system utilizes the electric motor for supplementary power at heavy power demand times.
Another hybrid drive I.C., electric propulsion combination is shown in U.S. Pat. No. 4,165,795 issued Aug. 28, 1979, wherein the I.C. engine is operated in an optimum mode at a substantially constant speed and power level in which the I.C. engine produces the least amount of pollutants.
As for operation of I.C. engine propelled systems, automobile manufacturers have struggled to control the air-fuel ratio of a mixture supplied to the engine to a stoichiometric mixture ratio for best conversion efficiency of a three-way catalyst in the exhaust system for best emission characteristics (see, e.g., U.S. Pat. No. 4,878,472 issued Nov. 7, 1989).